Aims: Typical tako-tsubo cardiomyopathy (TTC) mimics acute anterior myocardial infarction (AMI) and the differential diagnosis is challenging before coronary angiography (CA) is performed; it demonstrates reduced or absent antegrade flow in the left anterior descending artery (LAD) in AMI, whereas there is no such flow limiting in TTC. At the acute phase, we tested the usefulness of the distal LAD flow visualization by transthoracic Doppler echocardiography (TDE) to distinguish between these two diseases. For this purpose, we prospectively enrolled 28 consecutive patients with TTC (75 ± 10 years, 93% females) who were compared with 28 consecutive patients with AMI treated successfully by primary angioplasty (66 ± 12 years, 79% females). All the patients underwent the assessment of the distal LAD flow just before CA, using colour and pulsed-wave TDE. In addition, the symmetric involvement of wall motion abnormalities (WMAs) based on the extent of the disease far beyond one coronary territory in TTC was searched by TDE. Non-invasive coronary flow reserve (CFR) by TDE, in the distal LAD, was also performed within 1 day after admission.
Results: Before CA, the distal LAD flow was visible in 38 of 56 cases (68%) in the whole population, in all cases with TTC and in 10 cases with AMI (36%). The sensitivity (Se) and specificity (Sp) of the LAD flow visualization for the diagnosis of TTC were 100 and 64%, respectively, with a diagnostic accuracy of 82%. In comparison, the pattern of WMA yielded a Se of 75% and Sp of 86%, and a diagnostic accuracy of 80%. With the combination of both tools, the Se and Sp to detect TTC were 75 and 96% respectively, with a diagnostic accuracy of 86%. After CA, the acute CFR was less severely impaired in the TTC group when compared with the AMI group (2.2 ± 0.5 vs. 1.7 ± 0.6, P < 0.01) despite a worse LV systolic dysfunction.
Conclusion: Non-invasive evaluation of the distal LAD flow could be helpful to differentiate TTC from AMI, and its combination with the pattern of WMA improved slightly its diagnostic accuracy. Furthermore, the acute CFR is less severely impaired in TTC compared with AMI despite poorer LV systolic dysfunction, suggesting that other mechanisms than direct microcirculatory damage are also involved in the pathogenesis of WMAs in TTC.